The invention relates to a method for coding a sequence of digitized images with a plurality of image blocks as well as a corresponding decoding method. The invention also relates to corresponding coding and decoding devices.
Actual video coding standards (for example, see document [1], below) allow the coding of image sequences, wherein macro image blocks used for an estimation of movement are updated by means of an intra-coding mode. As a result, errors are not reproduced in the image sequence. Updating by means of intra-coding modes can be carried out at regular intervals or based on predetermined criteria. For other video coding methods, intra-coding modes, that refer back to several previously coded reference images, can be used. However, there are no mechanisms that allow an efficient video coding with inter-coding modes and intra-updating modes over error-prone networks.
The publication “Proc. Intl. Conf. On Image Processing ICIP, Lausanne, vol. 1, Sep. 16, 1996, pp. 763-766 (Liao et al)” describes an intra-update method for video coding via channels prone to errors. This method analyses the specific sensitivity of macro blocks for channel errors and obtains a specification for the intra-update modes.
The publication “Proc. IEEE ICASSP, San Francisco, vol. 3, Mar. 23, 1992, pp. 545-548 (Haskell et al)” describes several possible methods for resynchronizing movement-compensated videos that are adversely affected by ATM cell loss.
Accordingly, a system and method is needed for allow an efficient video coding with inter-coding modes and intra-updating modes over error-prone networks. As will be discussed below, a method is disclosed for coding a sequence of digitized images that uses a plurality of intra-coding and inter-coding modes as well as a plurality of reference images, to ensure a reliable reconstruction of the digitized images in error-prone networks.